In vivo dGEMRIC was validated in two ways: First, patients were imaged
before total knee replacement surgery; the joint was then obtained for
ex-vivo dGEMRIC (already validated against histology), and then with
histology directly. An example is shown in Figure 1. Secondly, a dGEMRIC
image was taken with the regular Gd(DTPA)2- contrast agent, and then
repeated (within a week or so) with a non-ionic contrast agent GdHPDO3A.
The two contrast agents have similar MW. The uniform distribution of the
non-ionic contrast agent provides further evidence that the non-homogeneous
distribution of the ionic contrast agent (Figure 2) is due to the
distribution of charge, or GAG concentration in the tissue.
Ionic contrast agent
Non-Ionic contrast agent
dGEMRIC (Gd(DTPA)2-) image vs. an image obtained with a non-ionic
contrast agent (GdHPDO3A). The non-ionic contrast agent distributes
uniformly in the cartilage.
For further details on these studies, please refer to:
Bashir A, Gray ML, Boutin R, Burstein D. In vivo imaging of GAG in
articular cartilage using delayed Gd(DTPA)2- enhanced MRI. Radiology 1997; 205: 551-558.
Bashir A, Gray ML, Hartke J, Burstein D. Nondestructive Imaging of
Human Cartilage Glycosaminoglycan Concentration by MRI. Magn Reson Med 1999; 41:857-865.
The final in vivo protocol is discussed in:
Burstein D, Velyvis JH, Scott KT, Stock KW, Kim YJ, Jaramillo D, Boutin
RD, Gray ML. Protocol issues for delayed Gd(DTPA)2- enhanced MR imaging
(dGEMRIC) for clinical evaluation of cartilage. Magn Reson Med